This invention relates to the assembly of seamed articles made from limp material, such as fabric. In particular, the invention relates to systems for automated, or computer-controlled, assembly of seamed articles from limp material.
Conventional assembly line manufacture of seamed articles constructed of limp fabric consists of a series of manually controlled assembly operations. Generally tactile presentation and control of the fabric-to-be-joined is made to the joining, or sewing, head under manual control. One drawback of this application technique is that the technique is labor intensive; that is, a large portion of the cost for manufacture is spent on labor. To reduce cost, automated or computer-controlled manufacturing techniques have been proposed in the prior art.
An automated approach to fabric presentation and control is disclosed in U.S. patent application Ser. No. 345,756. As there disclosed, pairs of belt assemblies are positioned on either side of a planar fabric locus. The respective belt assemblies are driven to selectively provide relative motion along a reference axis to layers of fabric lying in the fabric locus. A joining, or sewing, head is adapted for motion adjacent to the fabric locus along an axis perpendicular to the reference axis. The respective belts maintain control of the limp fabric in the region traversed by the sewing head, with the respective belts being selectively retracted, permitting passage therebetween of the sewing head as it advances along its axis of motion. With this approach, control of the limp fabric is permitted in the regions which are to be joined.
Systems for the manufacture of seamed articles from a strip of limp fabric disclosed in U.S. patent application Ser. No. 515,126 provide more precise "near field" control of limp fabric, that is fabric control in regions close to the sewing head. Those systems include a feeder for selectively feeding these strips of limp fabric in the direction of a first (Y) reference axis. Control of presentation may also be maintained in a second (X) axis perpendicular to and intersecting the Y axis.
In some forms, a folding apparatus controls the position of the fabric so that the strip of fabric is folded onto itself along a fold axis offset from the axis of feed (Y axis) so that there is a folded portion having an upper layer overlying a lower layer. A support is used to position the upper and lower layers of the folded portion in a substantially planar fabric locus.
In one form of those systems, the support includes a frame member, a support assembly coupled to the feeder, and a drive motor and an associated linkage for selectively positioning the frame member with respect to the support assembly in the direction of the X axis. A pair of lower belt assemblies is coupled to the frame member, where each lower belt assembly includes a plurality of continuous loop lower belts underlying the fabric locus. The lower belts are adapted on their outer, uppermost surface for frictional coupling with the lower layer of the folded portion. The lower belt assemblies are adjacently positioned along the X axis, with each assembly including an associated driver for selectively driving the lower belts so that the lower fabric layer coupled to those belts is positionable in the direction of the X axis.
A pair of upper belt assemblies is coupled to the frame member as well. The upper belt assemblies are adapted to be positioned to overlie the lower belt assemblies. Each of the upper belt assemblies includes a plurality of upper belts (which may be positioned opposite the respective lower belts). The upper belts have planar lowermost portions spaced apart from the uppermost of the lower belts. The upper belts are adapted on their outer, lowermost surface for frictional coupling with the upper layer of the folded portion. Each of the upper belt assemblies has an associated driver for selectively driving those upper belts so that the lower layer coupled to those belts is positionable in the direction of the X axis. The region between the lowermost portions of the upper belts and the uppermost portions of the lower belts defines the fabric locus, so that the fabric locus is substantially parallel to the plane formed by the intersecting X and Y axes.
In general, a computer-controller is used to selectively control the drivers for the respective belts so that the upper and lower layers may be substantially independently positioned in the direction of the X axis along the fabric locus. In alternative forms of those systems, the respective belt assemblies may be controllable in the Y axis direction as well, so that the upper and lower layers may be substantially independently positioned in the direction of both the X and Y axes along the fabric locus, thereby permitting control motion of the respective layers in those directions.
A fabric joiner, or sewing head, includes an upper assembly and a lower assembly. These upper and lower assemblies are adapted for tandem motion along the direction parallel to the Y axis between the upper belt assemblies and the lower belt assemblies. An associated driver provides control of the position of the upper and lower assemblies of the joiner along its axis of motion. The joiner is selectively operable to form seams in fabric in the fabric locus under the control of a computer-controller.
In one form of the systems of those systems, at least one pair of the pairs of the adjacent belt assemblies includes opposing pairs of closed loop belts and an associated controller adapted so that the pairs of the closed loop belts are selectively retractable in the X direction to permit passage of the joining head therebetween in the Y direction, for example, in the manner disclosed in U.S. patent application Ser. No. 345,756.
The joining head may include a needle assembly having a thread-carrying, elongated needle extending along a needle reference axis perpendicular to the fabric locus. In operation, the needle is driven through the fabric locus in a reciprocal motion along the needle reference axis. The needle assembly further includes an upper feed dog assembly which is responsive to an applied upper dog drive signal for selectively driving the uppermost layer of fabric in the region adjacent to the needle in the direction of an upper axis which is perpendicular to the needle reference axis.
A bobbin assembly is generally used in those systems and is adapted for interaction with the needle assembly to form the stitches of the seam. The bobbin assembly includes a lower feed dog assembly which is responsive to a lower dog drive signal for selectively driving the lowermost layer of fabric in the region adjacent to the needle in the direction of a lower axis which is perpendicular to the needle reference axis.
In one form of those systems, a controller generates a part assembly signal representative of the desired position of the junction of the layers of fabric relative to those layers. Registration sensors provide signals representative of the current position of the respective uppermost and lowermost fabric layers. A controller provides overall control for the belt assemblies as well as the feed dogs and needle and bobbin assembly rotational and feed dog control, in order to achieve coordinated motions of the respective assemblies. With this configuration, the respective belt assemblies provide far field, or global, position control for the upper and lower fabric layers. The feed dogs provide near field, or local, position control for the upper and lower layers of fabric in the regions near the needle of the joining head.
While the above-referenced systems do effectively provide approaches for the automated assembly of seamed articles, there are limitations in those operations particularly regarding the positioning, orienting and folding of limp fabric in preparation for joining of seams. Further, automated assembly systems require a feedback control system in order to accomplish these preparatory operations. In all such operations, it is important that accurate and repeated edge positioning of fabric be achieved in order to assure uniform quality of garment assembly. Moreover, these aspects are particularly important in view of desired high volume, and in view of the prior art requirement of specialized assemblies, requiring pattern- and size- dependent clamps or fixtures. Another factor for such automated assembly systems is that such systems must be cost effective compared with the existing approaches.
Accordingly, it is an object of the present invention to provide an improved system for automatic assembly of seamed articles.
Another object is to provide an improved automated assembly system for seamed articles including a relatively low cost optical feedback system controlling fabric location and orientation.
Yet another object is to provide an improved folding apparatus for folding fabric in automated seamed article assembly systems.